This invention relates to both an apparatus for and method of screening people and articles, to detect exposure and/or to decontaminate with respect to substances of interest, particularly, toxic materials, such as chemical warfare gases and vapours and the like from industrial accidents.
Rapid screening techniques are required to quickly identify people who may have been exposed to toxic emissions, notably either from chemical warfare gases and vapours or chemicals spilled or accidentally formed from industrial accidents. Often these substances are released or disseminated in liquid form, and the liquids have effectively low boiling points such that the vapours are readily emitted.
Following a chemical warfare agent attack, for example, numerous people could be contaminated, as for example in crowded metropolitan underground rail systems. Since nerve and chemical warfare agents are extremely toxic, quick response and remedial action is essential. If liquid agents were disseminated into closed areas, the contamination could be very high. Great care must therefore be taken to ensure that in a mixed population of victims or potential victims, those who are contaminated are quickly separated from those who are not. In the Tokyo Metropolitan Rail attack, sarin was used and the First Responders (i.e. emergency personnel such as Fire, Police or ambulance staff, who first arrived at the scene) were unable to separate contaminated from uncontaminated people. As a consequence, victims whose clothing had been contaminated with the sarin became sources of reliberation of the vapours, which then cross-contaminated people who were originally unaffected. Thus, the casualties from the attack were greatly multiplied. It is most desirable therefore to develop a quick screening system where individuals could pass through a walk-through portal, similar to Walk-Through Metal Detectors (WTMD) used in airports for screening passengers for concealed weapons. Just as WTMD systems detect the presence of metal objects, the inventor has realized that a similar screening system could be used to detect the presence of chemical agents. There is a need for easily deployed walk-through portal systems provided with air jets that can air brush people and speedily process possible victims on a walk-through basis.
The present invention is based on the realization that a curtain, using air or other gas, can quickly thermally desorb such high vapour pressure toxic materials which pass from the skin and/or clothing of the victims. The air is passed through a filtering clean up system to render it safe before re-emission. A pump is provided to draw air from the atmosphere, clean it before it is passed to blowers which direct air jets over the suspected victim(s) within the air portal device. To increase the efficiency of evaporation of toxic materials, the air flow may be preheated.
Such devices can be provided in a portable form such that they may be readily transported from site to site and quickly reassembled where chemical terrorism acts or industrial accidents may have occurred. Alternatively such portals can be permanently installed at critical sites.
The walk-through portal of the present invention can include a plenum which delivers a flow of high volume warm air at approximately 10,000 Litres/minute over the person under processing. The person walks into the portal and executes a 90xc2x0 turn so that the air jets, preferably heated, can blow over the front and back areas of their body and sweeps the warm air exhaust stream into a collecting plenum. A simple portable breathing mask might be provided so that the subject will not inhale chemical agents liberated from their clothing and skin. The air collecting plenum, handling about 2,000 L per person, (i.e. based on a 12 second time period for each person in the portal) will exhaust the collected air through a high volume filtering system. The exhaust filter abstracts any desorbed chemicals from the air flow before it is exhausted to the open atmosphere.
Any liquid chemical agent on clothing is liberated and either passes as whole liquid or thickened agent droplets into the plenum for subsequent removal by the charcoal filtering system, or the agents are vaporized in situ into the air flow and also effectively removed by the same filter. If the chemical droplets have absorbed into clothing, the flow of the warm air flow will greatly assist in their liberation. Some agents which have low viscosity and high vapour pressure are thickened by adding inert material. This produces a very viscous material, which readily adheres to surfaces and evaporates slowly, a persistent agent which is more difficult to clean up.
An analytical instrument can be used to make chemical measurements on the air flow exhausted through the plenum prior to filtering. One such instrumental method is Ion Mobility Spectroscopy (IMS); a successful means for detecting and identifying CW agents. However, many other techniques exist. An enrichment process can allow agents to be removed from the high volume air flow so as to be transferred into a much lower air flow compatible with instruments such as an IMS detector. Other instruments can be used to monitor the effluent such as fast gas chromatographs, IR analyzers, electrochemical cells and other such devices according to their analytical capabilities and speed of response for the analytes of interest.
In actual operation, especially where large numbers of individuals may need to be processed, speed is of essence and a number of such prescreening warm air only portals could be provided. The preliminary processing involves basic air decontamination; the individuals could be subsequently screened through a second portal which incorporates the chemical measurement means to check if decontamination was successful. Where the number of victims are few, a single portal can perform the functions of decontamination and contamination monitoring.
The portals could be constructed as portable devices or xe2x80x9cknock-downxe2x80x9d kits, allowing for ease of transport and rapid assembly at the site of the chemical release. Evidently, such portals could be permanently constructed for us in chemical plants or military installations where dangerous chemical materials are stored, handled, processed or positioned. Additionally, such portals could be used as security screens at airport check points.
In accordance with a first aspect of the present invention, there is provided a walk-through portal for at least one of detection of a predetermined substance on a subject and decontamination of a subject from a predetermined substance, the walk-through portal comprising:
an enclosure defining an examination zone and being substantially open on at least one side, to permit a subject readily to enter and to exit the examination zone;
a closure means for substantially closing off the examination zone from the exterior;
an inlet into the examination zone and an outlet from the examination zone; and
a pump for pumping a gas through the inlet into the examination zone, over a subject to entrain at least one of vapours and particulates from such substance, and out through the outlet.
The portal preferably includes at least one flexible screen, closing off the examination zone. More preferably, the walk-through portal is open on opposite sides thereof, to enable a subject to walk into the examination zone from one side and out from the examination through the other side, and the walk-through portal further includes flexible screens on both sides, closing off the examination zone.
Advantageously, the portal includes an output decontamination filter connected to the outlet from the examination zone, for ensuring that gas exhausted into the atmosphere is free from any contaminating substance and/or an inlet filter, mounted between the inlet and the examination zone, for filtering gas flowing into the examination zone.
Preferably, the walk-through portal includes an analyzer, connected to the outlet, for taking a sample of gas flowing through the outlet, whereby the analyzer determines the presence of said substance in the gas flowing through the outlet and/or a detection instrument connected to the inlet, for monitoring gas flowing into the examination zone for presence of contamination.
Instead of an open system, the portal can include a recirculation duct connected between the outlet and the inlet and a filter mounted in the recirculation duct, for cleaning gas exhausted from the examination zone of any contaminating substance, before the gas is recirculated back through the inlet into the examination zone.
In either version, the portal can include a supply of a decontamination agent, connected to the recirculation duct, downstream from the filter, for supply of a decontamination agent for one of neutralization, destabilizing and breaking down said substance.
An indicator can be connected to the analyzer and is operable to provide an indication as to whether a subject is or is not contaminated with said substance. A connection can be provided between the analyzer and the pump, for turning off the pump, after a predetermined period of time, when it is determined that said substance is not present, indicative that subject is not contaminated.
Another aspect of the present invention provides a device, for at least one of detection of a predetermined substance on an article and decontamination of an article from a predetermined substance, the device comprising:
an enclosure defining the examination zone, the enclosure being openable for insertion and removal of an article and being closable to close off the examination zone from the exterior;
an inlet into the examination zone and an outlet from the examination zone;
a pump for pumping a gas through the inlet into the examination zone, over the article to entrain at least one of vapours and particulates of said substance, and out through the outlet; and
an analyzer connected to the outlet, for sampling gas flowing through the outlet, whereby the analyzer determines the presence of said substance, indicative of contamination of the article by said substance.
Yet another aspect of the present invention provides a method of effecting at least one of detection of a substance on a subject and decontamination of the subject, the method of comprising the steps of:
(1) enclosing the subject in an examination zone substantially closed off from the exterior;
(2) passing gas into the examination zone, to entrain at least one of vapours and particulates of said substance; and
(3) withdrawing gas from the examination zone.